package com.example.springboot.config.interceptor;

import cn.hutool.core.util.StrUtil;
import com.auth0.jwt.JWT;
import com.auth0.jwt.JWTVerifier;
import com.auth0.jwt.algorithms.Algorithm;
import com.auth0.jwt.exceptions.JWTDecodeException;
import com.auth0.jwt.exceptions.JWTVerificationException;
import com.example.springboot.entity.User;
import com.example.springboot.exception.ServiceException;
import com.example.springboot.service.IUserService;
import com.example.springboot.common.Constants;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class JwtInterceptor implements HandlerInterceptor {

    @Autowired
    private IUserService userService;

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) {
        String token = request.getHeader("token");// 从请求头中获取token
        if (StrUtil.isBlank(token)) {
            token = request.getParameter("token");// 如果请求头中没有token，则从请求参数中获取
        }

        // 如果不是映射到方法直接通过
        if(handler instanceof HandlerMethod) {
            AuthAccess annotation = ((HandlerMethod) handler).getMethodAnnotation(AuthAccess.class);
            if (annotation != null) {
                return true;// 如果方法上有AuthAccess注解，则直接通过

            }
        }

        if (StrUtil.isBlank(token)) {
            throw new ServiceException(Constants.CODE_401, "无token，请重新登录");
        }

        // 获取 token 中的 user id
        String userId;
        try {
            userId = JWT.decode(token).getAudience().get(0);// 解码token，获取userid
        } catch (JWTDecodeException j) {
            throw new ServiceException(Constants.CODE_401, "token验证失败，请重新登录");// 如果解码失败，则抛出异常，提示用户登录
        }
        // 根据token中的userid查询数据库
        User user = userService.getById(userId);
        if (user == null) {
            throw new ServiceException(Constants.CODE_401, "用户不存在，请重新登录");
        }
        // 用户密码加签验证 token
        JWTVerifier jwtVerifier = JWT.require(Algorithm.HMAC256(user.getPassword())).build();// 创建JWT验证器，使用用户的密码作为密钥
        try {
            jwtVerifier.verify(token);
        } catch (JWTVerificationException e) {
            throw new ServiceException(Constants.CODE_401, "token验证失败，请重新登录");
        }
        return true;
    }
}
